import math
p = map(float, raw_input().split())
print("%.10f" %(math.sqrt((p[2] - p[0]) * (p[2] - p[0]) + (p[3] - p[1]) * (p[3] - p[1])))) import math math p = map(float, raw_input().split()) p map(float, raw_input().split()) map float raw_input().split() ().split () raw_input split print("%.10f" %(math.sqrt((p[2] - p[0]) * (p[2] - p[0]) + (p[3] - p[1]) * (p[3] - p[1])))) print "%.10f" %(math.sqrt((p[2] - p[0]) * (p[2] - p[0]) + (p[3] - p[1]) * (p[3] - p[1]))) "%.10f" math.sqrt((p[2] - p[0]) * (p[2] - p[0]) + (p[3] - p[1]) * (p[3] - p[1])) math.sqrt math sqrt (p[2] - p[0]) * (p[2] - p[0]) + (p[3] - p[1]) * (p[3] - p[1]) (p[2] - p[0]) * (p[2] - p[0]) p[2] - p[0] p[2] p 2 p[0] p 0 p[2] - p[0] p[2] p 2 p[0] p 0 (p[3] - p[1]) * (p[3] - p[1]) p[3] - p[1] p[3] p 3 p[1] p 1 p[3] - p[1] p[3] p 3 p[1] p 1 p = map(float, raw_input().split()) map(float, raw_input().split()) p
import math
p = map(float, raw_input().split())
print("%.10f" %(math.sqrt((p[2] - p[0]) * (p[2] - p[0]) + (p[3] - p[1]) * (p[3] - p[1]))))